1 files changed, 78 insertions, 0 deletions
diff --git a/bzipper_macros/src/impls/deserialise_enum.rs b/bzipper_macros/src/impls/deserialise_enum.rs
new file mode 100644
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+++ b/bzipper_macros/src/impls/deserialise_enum.rs
@@ -0,0 +1,78 @@
+// Copyright 2024 Gabriel Bjørnager Jensen.
+//
+// This file is part of bzipper.
+//
+// bzipper is free software: you can redistribute
+// it and/or modify it under the terms of the GNU
+// Lesser General Public License as published by
+// the Free Software Foundation, either version 3
+// of the License, or (at your option) any later
+// version.
+//
+// bzipper is distributed in the hope that it will
+// be useful, but WITHOUT ANY WARRANTY; without
+// even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Less-
+// er General Public License along with bzipper. If
+// not, see <https://www.gnu.org/licenses/>.
+
+use crate::Discriminant;
+
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::{DataEnum, Fields, Token};
+use syn::punctuated::Punctuated;
+
+#[must_use]
+pub fn deserialise_enum(data: &DataEnum) -> TokenStream {
+	let mut match_arms = Punctuated::<TokenStream, Token![,]>::new();
+
+	for (index, variant) in data.variants.iter().enumerate() {
+		let variant_name = &variant.ident;
+
+		let discriminant = Discriminant::unwrap_from(index);
+
+		let block = if matches!(variant.fields, Fields::Unit) {
+			quote! { Self }
+		} else {
+			let mut chain_commands = Punctuated::<TokenStream, Token![,]>::new();
+
+			for field in &variant.fields {
+				let field_ty = &field.ty;
+
+				let command = field.ident
+					.as_ref()
+					.map_or_else(
+						||           quote! { stream.take::<#field_ty>()? },
+						|field_name| quote! { #field_name: stream.take::<#field_ty>()? }
+					);
+
+				chain_commands.push(command);
+			}
+
+			match variant.fields {
+				Fields::Named(  ..) => quote! { Self::#variant_name { #chain_commands } },
+				Fields::Unnamed(..) => quote! { Self::#variant_name(#chain_commands) },
+				Fields::Unit        => unreachable!(),
+			}
+		};
+
+		match_arms.push(quote! { #discriminant => #block });
+	}
+
+	match_arms.push(quote! { value => return Err(::bzipper::Error::InvalidDiscriminant { value }) });
+
+	quote! {
+		fn deserialise(data: &[u8]) -> ::bzipper::Result<Self> {
+			::core::debug_assert_eq!(data.len(), <Self as ::bzipper::Serialise>::SERIALISED_SIZE);
+
+			let mut stream = ::bzipper::Dstream::new(data);
+
+			let value = match (stream.take::<u32>()?) { #match_arms };
+			Ok(value)
+		}
+	}
+}